Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G14/00—Condensation polymers of aldehydes or ketones with two or more other monomers covered by at least two of the groups C08G8/00 - C08G12/00
  • C08G14/02—Condensation polymers of aldehydes or ketones with two or more other monomers covered by at least two of the groups C08G8/00 - C08G12/00 of aldehydes
  • C08G14/04—Condensation polymers of aldehydes or ketones with two or more other monomers covered by at least two of the groups C08G8/00 - C08G12/00 of aldehydes with phenols
  • C08G14/06—Condensation polymers of aldehydes or ketones with two or more other monomers covered by at least two of the groups C08G8/00 - C08G12/00 of aldehydes with phenols and monomers containing hydrogen attached to nitrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G8/00—Condensation polymers of aldehydes or ketones with phenols only
  • C08G8/04—Condensation polymers of aldehydes or ketones with phenols only of aldehydes
  • C08G8/08—Condensation polymers of aldehydes or ketones with phenols only of aldehydes of formaldehyde, e.g. of formaldehyde formed in situ
  • C08G8/12—Condensation polymers of aldehydes or ketones with phenols only of aldehydes of formaldehyde, e.g. of formaldehyde formed in situ with monohydric phenols having only one hydrocarbon substituent ortho on para to the OH group, e.g. p-tert.-butyl phenol
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
  • C08L61/04—Condensation polymers of aldehydes or ketones with phenols only
  • C08L61/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L7/00—Compositions of natural rubber
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/06—Copolymers with styrene

Definitions

• This invention relates to a method of improving the tackiness of rubber compositions used in the preparation of moulded articles, particularly vehicle tires.
• Rubber articles are frequently made up of several layers each with the same or a different chemical basis. For ease of production the layers must adhere to one another adequately in the non-vulcanised state. This is particularly true of the manufacture of vehicle tires, wherein the layers have to adhere to one another quickly and firmly when the tyre blanks are built up. The assembled tire blank itself is required to hold together for a fairly long period and it is therefore important that the rubber mixtures used have an adequate tackiness. This property is termed “assembly tackiness" or “building tack.”
• tackiness is often taken to mean the flowing together to two surfaces. However, this effect depends substantially on the softness of the mixtures.
• tackiness is taken to mean the force which is required to pull apart two non-vulcanised mixtures which have been pressed together under certain defined conditions.
• Known tackifiers are colophony, hydrogenated and dimerised colophony, terpene resins and modified terpene resins, hydrocarbon resins based on unsaturated C 5 hydrocarbons, unsaturated C 9 hydrocarbons, dicyclopentadiene or coumarone, phenol resins of the novolak type, for example those obtained from alkylphenols having from 4 to 15 carbon atoms in the alkyl groups by reaction with formaldehyde in an acid medium, and alkylphenol resins prepared by reacting alkylphenols with alkynes, particularly acetylene.
• a phenol-crotonaldehyde novolak the phenol component of which comprises, for example, an alkylphenol and/or a diphenol, e.g resorcinol or hydroquinone.
• the crotonaldehyde may optionally be replaced by up to 50% formaldehyde.
• the rubber compositions into which the tackifier is incorporated are generally produced in internal mixers or on sets of rollers from a natural or synthetic rubber, e.g. styrene-butadiene copolymers, polybutadiene and mixtures thereof, fillers, processing agents and vulcanising agents. They must remain sufficiently tacky under the operation conditions, even when operation is interrupted for fairly long periods. With the known tackifiers, this is not always achieved or is only partly achieved. Moreover, the known tackifiers often do not achieve an adequate increase in tackiness.
• a natural or synthetic rubber e.g. styrene-butadiene copolymers, polybutadiene and mixtures thereof, fillers, processing agents and vulcanising agents. They must remain sufficiently tacky under the operation conditions, even when operation is interrupted for fairly long periods. With the known tackifiers, this is not always achieved or is only partly achieved. Moreover, the known tackifiers often do not achieve an adequate increase in t
• the modified alkylphenol novolaks used in the new method according to the invention are advantageously prepared by condensation of the phenol component (A), the at least trifunctional component (B) and formaldehyde (C) in the presence of a acid catalyst.
• the molar equivalent ratio of the components (A) and (B) to the formaldehyde (C) in the novolak prepared is generally in the range from 1:1.1 to 1:0.8, preferably from 1:1.05 to 1:0.9.
• the mono- and dialkyl phenols used as components (i) and (ii) respectively are preferably ortho-and/or para-substituted.
• Suitable alkyl groups include for example propyl, isopropyl, sec. butyl, n-butyl, tert. butyl, isobutyl, n-hexyl, octyl, isooctyl, nonyl, isononyl, dodecyl and isododecyl groups as well as higher alkyl groups and cycloalkyl groups, e.g. cyclohexyl groups.
• Suitable polyfunctional substances (B) include for example phenolic compounds, aminoplast forming agents, polyamides and etherified and unetherified methylol compounds.
• Suitable phenols include for example phenol, m-cresol, 3,5-dimethylphenol, pyrocatechol, hydroquinone and resorcinol, polynuclear phenols, e.g. diphenylolpropane and diphenylolmethane, and low molecular weight novolaks prepared from the above mentioned phenols and formaldehyde.
• Aminoplast forming agents having a total of at least six carbon and nitrogen atoms are preferred, e.g. melamine and formoguanamine and substitution products thereof such as acetoguanamine and benzoguanamine, and dicyanodiamide.
• Other substances which may be used as component (B) are for example polymeric amides of acrylic and methacrylic acid and functional derivatives thereof, e.g.
• polyamides from polyamines and polycarboxylic acids or aminocarboxylic acids for example the condensation products of hexamethylene diamine and adipic acid and the condensation products of dimerised fatty acids and aliphatic diamines such as ethylene diamine or diethylene triamine, and also polycaprolactam.
• Methylol derivatives of the at least trifunctional substances mentioned above may also be used as component (B).
• the use of etherified methylol compounds is advisable when the polyfunctional compounds themselves are not sufficiently soluble in the reaction mixture. This is true particularly of melamine and dicyanodiamide and their derivatives.
• the novolak resins are preferably prepared by simultaneously reacting together components (i) or (ii), (B) and the formaldehyde, which may be used as an aqueous solution and/or as a polymer, e.g. the trimer at a temperature in the range from 80° to 300° C.
• component (i) or (ii) with the formaldehyde in a first stage at a temperature of from 80° to 130° C. until the majority of the formaldehyde is used up, then to add component (B) and continue the reaction at a temperature of from 80° to 300° C. Afterwards in both cases the reaction product should be free of volatile components by distillation.
• Acids and acid anhydrides may be used as catalysts for the condensation.
• the following may thus for example be used; inorganic acids e.g. hydrochloric, sulphuric, phosphoric and phosphorous acids; carboxylic acids e.g. oxalic, maleic, fumaric, chloroacetic and trichloroacetic acids; sulphonic acids, e.g. benzenemono-, di- and trisulphonic acids, toluene sulphonic acids and alkane sulphonic acids; acid esters of phosphoric acid, e.g. diphenylphosphoric and monophenylphosphoric acids; and acid anhydrides, e.g. maleic anhydride, pyromellitic anhydride and trimellitic anhydride.
• inorganic acids e.g. hydrochloric, sulphuric, phosphoric and phosphorous acids
• carboxylic acids e.g. oxalic, maleic,
• the modified alkylphenol resins obtained are generally light yellow to brown solid resins. They generally have melting points in the range from 40° to 160° C. and are totally or to a far extent soluble in aromatic solvents.
• the rubber composition to which the tackifier is added may comprise a natural or synthetic rubber or a mixture thereof, for example a styrene-butadiene copolymer rubber or an ethylene-propylene-diene terpolymer rubber.
• the novolak is advantageously added to the rubber composition and is homogenised therewith at a temperature above the melting point of the novolak.
• the homogenisation is conveniently effected in a roller mill at a mixture surface temperature in the range from 100° to 120° C.
• One or more further ingredients selected from stearic acid, zinc oxide, processing adjuvants, anti-agers, vulcanising agents e.g. phenolic resins and especially sulphur, fillers and mineral oil may if desired be added to the mixture at this stage.
• an accelerator is generally added to the composition at a temperature below the activation temperature of the accelerator, e.g. at temperatures of up to 120° C.
• the "heat treatment” described here which brings about homogenisation is known per se.
• the effect of the novolak is particularly good when it is completely dissolved in the rubber phase and is not present in the mixture in the form of solid particles. This can virtually always be achieved by means of the "heat treatment” described.
• the resin can be admixed with the rubber composition and heated in any desired manner to the temperature required for melting of the resin thereby dissolving the resin in the rubber at any stage of the mixing process.
• a carbon black-rubber mixture e.g. 450 grams of a mixture of styrene-butadiene rubber and HAF carbon black containing 50 grams of HAF carbon black to 100 grams of styrene-butadiene rubber
• a carbon black-rubber mixture e.g. 450 grams of a mixture of styrene-butadiene rubber and HAF carbon black containing 50 grams of HAF carbon black to 100 grams of styrene-butadiene rubber
• further ingredients selected from stearic acid, zinc oxide, processing adjuvants, anti-agers, vulcanising agents, e.g. a phenol resin or sulphur, filler and mineral oil, and the modified alkylphenol novolak resin which improves the tackiness are mixed in one after the other.
• the mixtures are then rolled for five minutes at temperatures of from 100° to 120° C. (measured on the surface of the mixtures running on the rollers).
• the temperature must be significantly higher than the melting point of the resin used and may accordingly be increased even to above 120° C.
• Mixing is subsequently completed by adding an accelerator at conventional mixing temperatures, i.e. at temperatures at which the accelerator does not react, e.g. at temperatures of up to 120° C.
• compositions of formulae 1 to 4 as shown in Table 1 are produced using tackifier resins A to D prepared as described hereinafter.
• Resin A 594 g of isononylphenol, 69 g of 91% aqueous formaldehyde and 2 g of toluenesulphonic acid are refluxed at 100° to 110° C. for 3 hours. Subsequently, 73.3 g of hexamethoxymethylmelamine are added. The volatile components are then distilled off from the mixture until the product is at a temperature of 220° C. When distillation has ceased, the temperature is kept at 230° C. for 1 hour under a water-jet pump vacuum. 660 g of a light-coloured resin are obtained, melting point 94° C.; viscosity 125cP/20° C. (in 50% xylene solution).
• the preparation is analogous to Example 2 but, instead of 8.3 g of resorcinol, 16.5 g of resorcinol in 25 g of water are added. 650 g of a light brown resin are obtained; melting point 103° C.; viscosity 195cP/20° C. (in 50% xylene solution).
• a polyethylene film is first placed on a chromium plated metal sheet and a frame with internal measurements 110 ⁇ 110 ⁇ 2 mm is then placed over it.
• a film of polytetrafluoroethylene (PTFE) cleaned in trichloroethylene having longitudinal cuts therein and measuring 40 ⁇ 110 mm is placed against an inner edge of the frame.
• the remaining area of 70 ⁇ 110 mm is covered with a piece of cotton fabric.
• the rubber composition to be tested is then rolled out to form a sheet 2 mm thick the dimensions of which are such that it fills the entire frame.
• the narrow upwardly facing surface of the composition as well as a piece of cotton fabric of the same size are thinly coated with an adhesive solution [obtained from 100 T of polychloroprene, 5 T of MgO, 4 T of ZnO, 124 T of petroleum ether (boiling range 80° to 110° C.), 124 T of toluene, 124 T of ethyl acetate and 45 T of an alkylphenol novolak].
• the cotton fabric is placed with the coated side against the upper surface of the rubber composition and covered with a polyethylene film and a second chromium plated metal sheet.
• the assembly is compressed in a vulcanising press at room temperature or at the temperature specified hereinafter for five minutes to form an assembly of 2 mm thickness. This is then carefully removed from the frame in such a way that the PTFE film does not lift off.
• Strips 22.5 mm wide are cut off and, after removal of the PTFE film, pairs of strips are placed in a converted Shore hardness measuring apparatus provided with a square stamp with sides measuring 2 cm. The pairs of strips are compressed under a load totalling 10 kg for 90 seconds.
• Removal of the PTFE film Storage of strips with an exposed test surface for 24 hours at room temperature. Pressing two strips together and subsequently pulling them apart again.
• Removal of the PTFE film Storage of the strips with an exposed test surface for 30 minutes at 80° C. The cooling for 30 minutes. Pressing two strips together for 90 seconds and subsequently pulling them apart again.
• Removal of the PTFE film Storage of strips with an exposed test surface for 30 minutes at 80° C. Then storage at room temperature for 24 hours. Pressing two strips together for 90 seconds and then pulling them apart again.
• Test 2 show that the tackifying effect of the resins A to C used according to the invention is not affected when compositions according to formula I are stored with their surfaces exposed, i.e. unprotected, and in many cases tackiness is even increased compared with a freshly produced test surface (Test 1).
• the comparison mixture without resin has very low tackiness.
• the known standard commercial tackifier resin which is obtained by reacting p-tert butylphenol with acetylene causes a considerable increase in tackiness.
• the resins A to C used according to the invention cause an even greater increase which is significant in Tests 2, 3, 4 and 6 and is very marked in Test 5.
• EPDM rubber of the "sequence type" yields compositions having particularly poor tacky properties. Test values ranging from usable to very good are however obtained with such compositions if they are preheated for some time before being pressed together. The optimum preheating conditions have to be determined for each different case by trial and error. In general, the conditions given for Tests 3 and 4 above have proved effective.
• Table 4 clearly shows that a substantial increase in tackiness is obtained by incorporation of resin A and the increase is much greater than that obtained with compositions without resin or with the resin from p-tert butylphenol and acetylene.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Laminated Bodies (AREA)

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Cited By (13)

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• 1975
  • 1975-08-23 DE DE2537656A patent/DE2537656C3/de not_active Expired
• 1976
  • 1976-08-02 US US05/710,548 patent/US4167540A/en not_active Expired - Lifetime
  • 1976-08-20 GB GB34866/76A patent/GB1500671A/en not_active Expired
  • 1976-08-20 AT AT621476A patent/AT355294B/de not_active IP Right Cessation
  • 1976-08-20 FR FR7625336A patent/FR2329678A1/fr active Granted
  • 1976-08-20 IT IT26428/76A patent/IT1065705B/it active
  • 1976-08-21 JP JP51099238A patent/JPS5235237A/ja active Granted

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